1. Field of the Invention
The present invention relates to fluid powered actuator systems for operating a mechanism, such as opening an aircraft door in an emergency; and more particularly to an apparatus which regulates the fluid flow to control the speed of the actuator.
2. Description of the Related Art
Commercial aircraft incorporate mechanisms for opening the doors of the passenger cabin in the event of an emergency. One known emergency door activating mechanism utilizes a piston/cylinder assembly that is operatively connected between the body of the aircraft and the door. A reservoir of gas, such as nitrogen, under high pressure is connected to the cylinder. When it is desired to open the door, the pressurized gas is released from the reservoir and applied to the cylinder thereby rapidly moving the piston and opening the door. International Patent Application PCT/EP2003/012374 and U.S. patent application Ser. No. 11/045,205 filed on Jan. 28, 2005 describe hydraulic systems for operating aircraft doors during an emergency.
Although the emergency door activation system must rapidly operate the door to a fully open position, it should do so without damaging the door and other parts of the aircraft. It should be recognized that in many emergency situations, the aircraft is not severely damaged and can be repaired for subsequent use. As a consequence, activation of the emergency door system ought not result in further aircraft damage which results in additional repair costs.
It is therefore desirable that the hydraulic operating mechanism apply the pressurized fluid to the actuator in a controlled manner so that the actuator does not operate at an excessive speed.